1. Field of the invention
This invention relates to a device designed to characterize the sensitivity to acceleration of measuring instruments such as accelerometers, rate gyros or gravimeters. It more particularly concerns the calibration of such instruments when they are rigidly mounted on the structure of a space vehicle or located on a platform decoupled from the structure, or when they are located on a platform decoupled from a ground-based support frame.
2. Description of the Prior Art
Means used on board the French CASTOR-D5B satellite to characterize the ultra-sensitive "CACTUS" triaxial electrostatic accelerometer are already known through ONERA publication No. 1976-5, "LES ESSAIS EN ORBITE DE L'ACCELEROMETRE CACTUS" (orbital testing of the CACTUS accelerometer), DELATTRE and al., and by the article entitled "The CACTUS ACCELEROMETER" which appeared in AGARDograph No. 254, Advances in Inertial Navigation Systems and Components, April 1981, pages 5-1 to 5-10.
In these documents, the accelerometer is placed in the center of mass of the satellite. Mechanisms move weights to off-center the satellite by known amounts. Flywheels control the constant speed rotation of the satellite in order to create a centripetal acceleration, within the axis system of the accelerometer, perceived as an acceleration with constant modulus and direction.
A first drawback of this technique is to impose a slow rotation on the satellite, which is not possible when the satellite needs to be stabilized in attitude and/or carries instruments pointed in one direction in space. A second drawback of the known process is that the calibration acceleration is difficult to distinguish from accelerations communicated to the satellite by external forces such as aerodynamic drag, radiation pressure, etc. Consequently the characterization precision of the accelerometer is limited, typically a relative precision of 10.sup.31 2, and means described are not applicable when greater precision is required.